I have successfully installed it on my LG L70 D320n with CM12 (I have Factory reset my phone using LG Flash Tool 2 times, meaning download mode, root and boot unlock all again from stock.) But here is what I have learned from experience.
prerequisites :LG Drivers, Java (both standard and Development 32 bit even if on 64bit Windows OS), ADB, fastboot and drivers (newest v1.4.2) from here"
http://forum.xda-developers.com/showthread.php?t=2588979" (remember to install drivers with it), and most importantly CM12 Rom installed with PhilZ recovery (recommended).
Step 1 : after you have all the requirements enable Android Debugging in Smartphone and plug into Computer.
Step 2 : goto My Computer, System Properties, Device manager, expand the first "Android Device tap", right click whats expanded (under it), click "update drivers", "browse my computer for drivers", "Let me pick......" at bottom of window, unselect "show compatible hardware", then chose "Google, Inc." as manufacturer and "Android ADB Interface" as model.click next, yes and done.
Step3 : Reboot to recovery, make backup, make sure USB storage is not mounted, run the CM12 script.
Step 4 : After the script has successfully installed, you will see that Cache, and data won't be mounting, next go to PhilZ, "Wipe and format", click "wipe User Media", and then "Custom format Options", "format /data and /data/media". then you will be able to mount cache and data. (this is why I have recommended PhilZ recovery as it has advanced format options)
Step 5 : Then take your usual steps to wipe, format, restore or install cm12.
Enjoy, hope this helps.